Plotting device



June 15, 1943. A'. l.. THuRAs-roN -ETAL 2,321,955

PLOTTING DEVICE Filed April 14, 1942 s sheets-sheet 1 Iii l5 INVENToRs Hem/w? L7M/6MM June 15, 1943. A. l.. 'rHuRsroN ETAL 2,321.955

PLoTTmG DEVICE Filed April 14, 1942 s sheet-sheet 2 un nh .......d-r. v........

; i@ Www Syffo/f/ June 15,- 1943. A.A 1.. TH'USTON ETAL 2,321,955

A PLOTTING EvI'cE Fild April 14, 1942 5 Sheets-Sheet 3 :"l'l'l'l'l'lFl'l'l loo |110 12o' 15o 14o 150.160 wo leo |901 i60 WQ |80 |90 200 ZIO 220 Illllllll lNVENTOR cover plate II inplace; `S'pa'cerwashers Patented June 15,` 1943 Arthur L Thurston,

-Wantagm and Beauregard i Sweeney, Great Neck, N. Y.,

assignors to Cox &. Stevens-AircraftCorporation, .Mineola, N. Y.,

a .corporation VApplication'A1i'l1i,1942, Serial No. 438,966

-- 4.V Claims.

Our invention relates to'drafting or plotting de-l It is especially, though not necessarilyfgj' vices. designed for use in aircraft where weight must be kept to a minimum and space is more or less: limited. 'Moreparticu'larlm the'invention relates to a parallel motion device' for navigational plot-n ting.

compact device'whereinjf'a straight edge'v or ruler, as itis moved at will over theplotting surface, remains parallel to any preselected line' or direction. f

Previously known devices of this character have made use of a systemof` cords attached to they ruler or straight edge afd running over pulleys, or of parallel linkages yof one sort or another.'

' The first of such deviceshasonly a limited rangefy of angular vmovement and is not suitable for navigational plotting. The latter, although satisfac-y tory in some respects', isi` muchtoo heavy for Fig. 5 is an enlarged planv View, partly broken away," of the vso-callecl movable member;` y Figs. 6 andA 7 are sectionalviews 'on the lines 6 6 and 1'l, respectively, of Fig. 5;

` Fig. 8 is a plan view of another .embodiment of Y the invention, and

Fig. 9 is an 'enlarged section. on line Fig. 8.

Referring to Fig. 1, the device comprises a fixed member I adapted for. attachmentv to. a drafting board or other plotting surface; a rider or movable member 2 carrying a plotter or ruler 3; and a pair of rack arms 4-.4 joining the fixed and movy able members.

The x'ed member I, Y(see Figs. 2V and .3) preferably' comprises anv attachment plate El bearing ions '8-8 and 9+-9 mounted on the studs; two

rack retainers IDL-I 9;

latter to the "board .by means of screws or bolts. The two outer studs 6-6 are tapped to -take screws I3`I3 which secure the Ill-I4,

The object of the invention is to provide a light,

and' cannot be u'sed effectively in aircraft because of' and'al cover plate Il. "Holes I2 are formed'in the attachment plate 5 'for fastening'the having thesame thickness 'as that of the rack retainers lll-I0 are used above and below the two inner pinions 9,-9V A spring I5 holds each rack 4 in engagement with its associated outer pinion 8.

The two inner pinions 9--9| are locked'together by any suitable means such as that shown, consisting of cutting away adjacent portions of the Itwo pinions to receive a tie plate -IB and soldering the latter in place. All pinions are of the same diameter and pitchl and the studs'- are so located that the adjacent pinions are in accurate mesh with each other.

Referring to Fig. "I, the movable member 2, it will be noted, is similar to the xed member I in that it includes a body plate I1 bearing four studs I8, whichv carry four pinions I9 having the same diameter and pitch as those of the xed member I, and spacer washers 20, cover plate 2l, rack retainers 22 and springs 23 whichare the same as to structure and function as the corresponding parts fof the xed member.- -The pinions i9 in the movable member, however, are not locked but are free to rotate.

The body plate I1 is lobed as at 24. To this lobe is rigidly attached a hollow post member 25 on the lower end of which are two cylindrical bearing surfaces 26 and 21 separatedby la spacer flange 28. A hole inthe plotter member 3 ts smoothly on the surface 26Aand a hole in a doubleended pointer member 29 ts smoothly on the surface 2l.

The central portion of the pointer member 29 is pressed against the under surface of the body plate byv one or more spring clips (not shown) secured. to the latter, and the outer ends of said member are bent downward to lie on the upper surface of the plotter member 3. The indicating edges of the pointer 29 are in a line passing through the center of rotation of the pointer.

A clamp member 3l withv a wide flange 32 and a threaded end 33 is inserted in the hollow of the post memberY 25 and held by a winged clamp nut 34. The-length of the cylindrical surface 26 is less` than the thickness of the plotter member 3 so thatwhen the nut,34 is tightened, the plotter member is held by beingV clamped between the flange, 28 of the post, member and theflange 32 of the clamp member. A stud 35 on the clamp member registers with a corresponding hole in the post member and prevents the clamp member rrcm turning as the clamp nut 3 5. is turned..

The plotter member 3 is preferably `made of transparentmaterial and has-scales of distance 36-3 inscribed along its upper and lower edges lower ends of the rack arms to keep the movable a member 2 from sliding off these ends.

Referring to Fig. 8, an alternative arrangement of the device consists of a fixed member 4 I, a movable member 42, a plotter 3 and a pair of rack'k arms 4 joining the xed and movable members.

The xed member is similar to that of the embodiment shown in Figs. 1 to 4, and includes an attachment plate 5 bearing four studs 6 6- and 1 1, outer pinions 8 8, rack retainers I0 I0, a cover` plate I I, spacer washers I4 I4 and springs I5 I5. Instead of having the inner pinions locked however, freely turning pinions 49-49 are mounted on the inner studs 1 1. These pinions are identical with the outer pinions and are in mesh with the latter and with each other, their action being the same as that of the pinions in the movable member of the plotter shown in Figs. 1 to 7. v

I The movable member 42 includes a central plate 50 from which extend two arms 5I 5I. At the outer end of each of these arms there is rigidly attached, as by soldering, brazing or other suitable means, a segment of gear 52, of the same diameter and pitch as the pinions of the fixed member. The center spacing of these segments :i

is the same as that of the outer pinions 8 8 of the xed member. A rack retainer 53 is pivotally attached at the center of each of these segments, the attachment being by means of a rivet 54 and a spacer tube 55, the latter turning freely in a hole 56 in the center of the segment. The springs 23-23 hold the racks 4 4 in engagement with the segments.

A hollow post member 51 having its post portion 58 extending up through a hole in the center of -1 the plate 5D, is rigidly attached to the .latter by soldering, riveting or other suitable means. The flange portion of the post member has an outer cylindrical surface 59 on which a hole in the plotter ts smoothly for turning. Means for clamping the plotter consisting of a flanged clamp member 60 and a winged clamp nut 34 are similar in construction and action to those described above for the movable member 2.

Turning on the post 58 is a double-ended pointer 62, the central portion of which is pressed against the plate 50 bymeans of two springclips 63 riveted to the arms 5I. The outer ends of the pointer are bent down to lie on the upper surface of the plotter.

The plotter and rack members are the same as for the example shown in Figs. l to 7 except that the latter are reversed so that the stops 40 are at the upper end to prevent the racks from sliding out of the fixed member.

From the foregoing it will be seen that one'A member-either the fixed or the movable pro vides a fixed segment of gear teeth at each side while the other member has at eachside a rotatable pinion, both members having rneansto.,7

hold the rack teeth in engagement with the gear teeth.

As the movable memberV is swung from side to side, the rack members turn on the fixed gears,

and if this movement is merely swinging, the` "paralle1. vmember may be made up of ar'combination of racks also turn through an equal travel on the outer rotatable pinions, so that the movable member has parallel motion. If the movable member is moved toward and from the fixed member, the intermeshing of the rotatable gears insures that there will be equal motion along the tWo rack arms, so that this motion will also be Since any motion ofvlthe'movable these two motions, it is obvious that the movable member will remain parallel when moved to any position on the board.

To use the device for plotting, the edge of the pointer is aligned with the meridian on the chart which is readily" visible through the transparent plotter. The clamp nut is then loosened and the plotter turned until the desired course or azimuth angle on the compass rose registers with the pointer edge and the clamp nut is tightened. The edge of the plotter may then be moved to any position on the chart for plotting. thiscourse.

'I he advantages of a plotting device characterized as above set forth are obvious and vneed not be again repeated. Suice it to say that in aircraft navigation it finds its greatest utility.

While we have described our 'invention in detail in its present preferred embodiment, it will be obvious to those skilled in the art, after understanding our invention, that various changes and modifications may be made thereinwithout departing from the spirit or scope thereof. We aim in the appended"claims to cover all "such ymodifications and changes.

Y `We claim as our invention:

l. For use in association with a plotting surface, aplotting device including separate assemblies, one of which is adapted for attachment relatively to the plottingsurface and the other of which is freely movable toward` and away from the attached assembly; each said assembly comprising a mounting means andat least two gear elements, the gea'r elements of at least one said assembly being freelyrotatable; and parallel rack bars connecting said assemblies and meshing each with at least one gear element of each assembly, said` rack bars by their meshing engagement with said freely rotatable gear elements being adapted to admit of the movement of one said assembly toward and away from the other.

2. For use in association with a plotting surface, a plotting device including separate assemblies, one of which yis adapted for attachment relatively to the plotting surface and the other of which is freely movable in an' arcuate path over said plotting surface; each said assembly comprising a mounting means and atleast two gear elements; and parallel rack bars connecting said assemblies and meshing each with at least one `gear element of each assembly,

said rack bars .by their meshing engagement with said gearfelements being adapted lto admit of the arcuate movement of said movable assembly'as aforesaid.

3. For use in association vwith aplotting lsurface, a plotting device including separate assemblies, one of which is adapted for attachment .ments; and parallel rack bars connecting said v assemblies and meshing each with at leastjone gear element of each assembly, said rack bars by their meshing engagement with said gear elements being adapted to admit of the arcuate movement of one said assembly and by their meshing engagement with said rotatable gear elements being adapted to admit of movement oi one said assembly toward and away from the other.

4. For use in association With a plotting surface, a plotting device including separate assemblies, one of which is adapted for attachment relatively to the plotting surface and the other of which is freely movable toward and away from the attached assembly as Well as in an arcuate path over said plotting surface; one said assembly comprising a mounting means and a train of intermeshing freely rotatable gear elements and the other said assembly comprising a mounting means and at least two non-rotatable gear elements; parallel rack bars connecting said assemblies and meshing each with at least one gear element of each assembly, said rack bars by their meshing engagement with said gear elements being adapted to admit of the arcuate movement of one said assembly and by their meshing engagement with said rotatable gear elements being adapted to admit of movement of one said assembly toward and away from the other, and spring means carried by each said assembly for holding said rack bars yieldingly in mesh with said gear elements in al1 positions oi adjustment of said movable assembly.

ARTHUR L. THURSTON.

BEAUREGARD SWEENEY. 

